John S. Green

Effects of Resistance, Endurance, and Concurrent Exercise on Training Outcomes in Men

UNLABELLED The specificity of training principle predicts that combining resistance and endurance training (concurrent training) could interfere with the maximum development of strength and endurance capacity that results from either type of training alone. PURPOSE To determine whether endurance and resistance training performed concurrently produces different performance and physiologic responses compared with each type of training alone. METHODS Untrained male volunteers were randomly assigned to one of three groups: endurance training (ET, N = 12); resistance training (RT, N = 13); and concurrent training (CT, N = 16). The following measurements were made on all subjects before and after 12 wk of training: weight, percent body fat, peak oxygen consumption (VO(2peak)), isokinetic peak torque and average power produced during single-leg flexion and extension at 60 and 180 degrees.s, one-repetition maximum (1RM) leg press, 1RM bench press, vertical jump height, and calculated jump power. RESULTS Weight and lean body mass (LBM) increased significantly in the RT and CT groups (P < 0.05). Percent body fat was significantly decreased in the ET and CT groups. VO(2peak) was significantly improved only in the ET group. Peak torque during flexion and extension at 180 degrees.s(-1) increased in the RT group. Improvements in 1RM leg press and bench press were significant in all groups, but were significantly greater in the RT and CT compared to the ET group. Jump power improved significantly only in the RT group, and no group showed a significant change in vertical jump height. CONCLUSIONS Concurrent training performed by young, healthy men does not interfere with strength development, but may hinder development of maximal aerobic capacity.

Heart disease risk perception in college men and women.

Abstract The authors sought to assess the perception of risks for coronary heart disease (CHD) in college men and women. They surveyed 470 undergraduates from 2 major 4-year institutions who completed a questionnaire that measured perceived risks for heart disease. Sixty-eight percent of the respondents rated their risks as lower or much lower than those of their peers, indicating a clear optimistic bias. The research also revealed that the students who exercised regularly rated their risk of coronary disease lower than those who did not do so. In addition, women perceived a number of risk markers to be more potent or causative factors than men did. A significant number of participants did not comprehend commonly understood causal relationships associated with heart disease risk. The findings in this preliminary investigation suggest that college men and women do not accurately perceive their risks for developing heart disease.

The effects of endurance training on functional capacity in the elderly : a meta-analysis

In this investigation, meta-analysis was used to delineate exercise induced changes in the VO2max of older individuals and test a null hypothesis of no significant training effects. Parameters included in the analysis were age of the subjects, length of the training regimen, frequency and duration of exercise bouts, pretraining VO2max, posttraining VO2max, and the difference between pretraining and posttraining VO2max (delta VO2max). Effect size for training-induced improvements in VO2max was calculated, corrected for bias, weighted, and analyzed according to contemporary meta-analysis procedures. The mean effect size was found to be 0.65 standard deviation units, representing an improvement in oxygen consumption of 22.8%. The mean effect size was also significantly different from 0 (P < 0.0001), and the null hypothesis was rejected. Stepwise regression analysis indicated that length of training, pretraining VO2max, and duration of training bouts accounted for 59% of the total variation in delta VO2max. In addition, age was found to be inversely correlated with pretraining VO2max (r = -0.56, P = 0.002), and delta VO2max (r = -0.56, P = 0.003). It was concluded that endurance training significantly increases functional capacity in the elderly, and that the increase is related to subject age, duration of exercise bouts, length of the training regimen, and pretraining VO2max.

Generalized abdominal visceral fat prediction models for black and white adults aged 17–65 y: the HERITAGE Family Study

OBJECTIVE: To determine if the relationship between abdominal visceral fat (AVF) and measures of adiposity are different between Black and White subjects and to develop valid field prediction models that accurately identify those individuals with AVF levels associated with high risk for chronic disease.DESIGN: Cross-sectional measurements obtained from 91 Black men, 137 Black women, 227 White men, and 237 White women subjects, ages 17–65 y, who were participants in the HERITAGE Family Study, both at baseline and following 20 weeks of endurance training.MEASURMENTS: AVF, abdominal subcutaneous fat (ASF), abdominal total fat (ATF), and sagittal diameter (SagD) were measured by computed tomography (CT). Body density was determined by hydrostatic weighing and was used to estimate relative body fat. Arm, waist (WC), and hip circumferences and skinfold thickness measures were taken, and BMI was calculated from weight (kg) and height (m2). Since CT abdominal fat variables were skewed, a natural log transformation (Ln) was used to produce a normal distribution. The General Linear Model (GLM) procedure was used to test the relationship between AVF and two different groups of variables—CT and anthropometric.RESULTS: The AVF of White men and women was significantly higher than that of Black men and women, independent of BMI, WHR, WC, and age, and was greater for men than for women. The CT model showed that the combination of SagD, Ln (ASF), age, and race accounted for 84 and 75% of the variance in AVF in men and women, respectively. The anthropometric model provided two valid generalized field AVF prediction equations. The Field-I equation, which included BMI, WHR, age and race, had an r 2 of 0.78 and 0.73 for men and women, respectively. The Field-II equation, which included BMI (women only), WC, age, and race, had an r 2 of 0.78 and 0.72 for men and women, respectively. The field model equations became less accurate as the estimated AVF increased.CONCLUSIONS: (1) At the same age and level of adiposity, Black men and women have less AVF than White men and women. These differences are greater in men than in women. (2) The field regression equations can be generalized to the diverse group of adults studied, both in an untrained and trained state. However, their accuracy decreases with increasing levels of AVF.

Electrocardiograms of collegiate football athletes.

The prevalence of electrocardiogram (ECG) abnormalities in American collegiate football athletes is virtually unknown.

Comparative efficacy of water and land treadmill training for overweight or obese adults.

PURPOSE No known previous research has been published to explore the efficacy of underwater treadmill (UTM) exercise training for the obese. Thus, the purpose of this study was to compare changes in physical fitness, body weight, and body composition in physically inactive, overweight, and obese adults after 12 wks of land treadmill (LTM) or UTM training. METHODS Fifty-seven physically inactive, overweight, and obese men (n = 25) and women (n = 32) participated in this investigation. The mean +/- SEM age, weight, body mass index (BMI), and V O2max upon entry were 44 +/- 2 yr, 90.5 +/- 2.4 kg, 30.5 +/- 0.7 kg.m, and 27.1 +/- 0.7 mL O2.kg.min, respectively. Subjects were randomly assigned to exercise three times per week for 12 wk on either LTM (n = 29) or UTM (n = 28) matched for intensity and volume. Session volume was progressively increased from 250 to 500 kcal per session by week 6 and remained at 500 kcal through week 12. Before and after training, V O2max was assessed by the Bruce treadmill protocol with open-circuit calorimetry, and body composition was assessed by dual-energy ray absorptiometry. Data were analyzed by a 2 (training) x 2 (exercise mode) x 2 (gender) ANOVA repeated across training (alpha = 0.05). RESULTS Training responses were not different between genders. After either UTM or LTM training, V O2max was significantly increased (+3.6 +/- 0.4 mL O2.kg.min), whereas body weight (-1.2 +/- 0.3 kg), BMI (-0.56 +/- 0.11 kg.m), body fat percentage (-1.3% +/- 1.3%), and fat mass (-1.1 +/- 0.3 kg) were significantly reduced (pooled means for UTM and LTM). Regional leg lean body mass (LBM) was significantly increased with both CTM and UTM (0.4 +/- 0.3 and 0.8 +/- 0.2 kg, respectively). An increase in total LBM approached significance with UTM training only (+0.6 +/- 0.3 kg, P = 0.0599). CONCLUSIONS UTM and LTM training are equally capable of improving aerobic fitness and body composition in physically inactive overweight individuals, but UTM training may induce increases in LBM.

Menopause, estrogen, and training effects on exercise hemodynamics: the HERITAGE study.

PURPOSE To investigate the influences of menopause, hormone replacement, and endurance exercise training on cardiovascular hemodynamics and oxygen uptake parameters during exercise in women. METHODS Subjects were 338 premenopausal women, 29 postmenopausal women taking hormone replacement, and 28 postmenopausal women not taking hormone replacement, all enrolled in the HERITAGE Family Study. Hemodynamic and oxygen uptake data were gathered on a cycle ergometer at 50 watts (W), 60% peak oxygen uptake, and at peak exercise, both before and after a 20-wk regimen of endurance exercise training on a cycle ergometer. RESULTS Systolic blood pressure (SBP) during peak exercise was found to be an average of 14 mm Hg less in postmenopausal women receiving hormones than in those not receiving hormones. Furthermore, menopause was associated with a 26.2 mm Hg higher SBP at 50 W power output, which remained physiologically significant after adjustment for age. At 50 W, postmenopausal women not taking hormones showed a 13.8 mm Hg greater training-induced reduction in SBP than those taking hormones. CONCLUSION It was concluded that hormone replacement may be associated with a vasodilatory reserve at high exercise intensities and that endurance exercise training elicits favorable hemodynamic and oxygen uptake adaptations during exercise that are, in most instances, independent of menstrual status or hormone replacement.

Endurance Training, Cardiovascular Function and the Aged

SummaryIndependent of disease, age-associated changes in cardiovascular function include anatomical, physiological, and haemodynamic alterations that are generally without pathological consequence. Decrements in adrenergic receptor response, arterial distensibility, ventricular compliance, and contractile performance seem to be compensated for by enhanced atrial contribution to ventricular filling, prolongation of systole, and increased reliance on the length-tension relationship of cardiac muscle. Summarily, these compensations constitute increased utilisation of the Frank-Starling mechanism.Endurance training beneficially alters aging cardiovascular function both at rest and during exercise. An increase in end diastolic volume and ejection fraction demonstrate an enhancement of the length-tension relationship of myocardial tissue in maintaining resting and exercise cardiac outputs. The decline in maximal cardiovascular function is not preventable. It was also concluded that endurance exercise improves clinical and psychosocial factors that enhance the quality of life for elderly individuals.Future research efforts should attempt to determine if and by what mechanisms endurance training may contribute to the regression of atherosclerotic lesions and the development of collateral vessels in senescent myocardium.

Morphological profiles for first-year National Collegiate Athletic Association Division I football players.

We are aware of no published research in which the morphological profiles of first-year collegiate football players are characterized. In light of the known association between obesity and cardiovascular disease and recent data suggesting an increased frequency of obesity and early death in professional football players, we have compiled a morphological profile of 65 freshman and transfer recruits (age = 18.4 ± 1.2 years) from a National Collegiate Athletic Association (NCAA) Division I football program. Measured variables included height (HT), body mass (BM), and body fat percentage (BF) (hydrostatic method). Body mass index (BMI) was calculated using HT and weight variables. Individuals were grouped by player position for descriptive statistical analysis. The means for all 65 players were as follows: HT = 189 ± 7 cm, BM = 106.5 ± 4.8 kg, BF = 15 ± 7%, and BMI = 29.8 ± 4.7. Mean data from these collegiate athletes were compared to recently published data from professional players. By comparison, the average HT, BM, BF, and BMI of the professional football athletes were 188 ± 4 cm, 107 ± 4.8 kg, 14 ± 5%, and 30.1 ± 1.9, respectively. While the average BMIs of the collegiate athletes in this study would be classified as overweight or obese, the BFs were found to be within an acceptable range for health status. These data provide important indicators of morphological characteristics and BM health risks of new football recruits at a Division I university. The data presented also provide an historical basis for (a) evaluating both the conditioning of first-year incoming athletes, (b) determining the physical development of the athletes as they progress through the training program, and (c) charting the morphological changes that occur in collegiate football throughout time that may contribute to increased health risks to the athletes.

DEXA or BMI: clinical considerations for evaluating obesity in collegiate division I-A American football athletes.

Objective:To evaluate the relationship between body mass index (BMI) and %body fat (%Fat) in collegiate football athletes (FBA) compared with age-matched/gender-matched general population volunteers (comparison group, CG) and compare body composition and overweight/obese frequencies by BMI between FBA and CG. Design:Cross-sectional. Setting:Two Division I-A (D-IA) universities in Texas. Integrative Health Technologies (San Antonio, Texas) laboratory. Participants:Football athletes (n = 156, 20.0 ± 1.3 years, 185.6 ± 6.5cm, 103.3 ± 20.4 kg). Comparison group (n = 260, 21.5 ± 2.7 years, 179.0 ± 7.6 cm, 86.3 ± 20.9 kg). Statistical Analysis:Body mass index and bone densitrometry (DEXA) body composition were assessed. Regression was used to predict %Fat from BMI in CG and FBA. To compare %Fat, fat mass (FM), fat-free mass (FFM), and weight (WT) between CG, FBA, linemen, and non-linemen, 1 × 4 analysis of variance was used. Chi-square analysis was used to compare the frequency of BMI ≥25 between groups. Results:Body mass index differently predicted %Fat for CG (r2 = 0.643, SE = 6.258) and FBA (r2 =0.769, SE = 4.416). Body mass index cutoffs for overweight/obese corresponded to the following %Fat in each group [BMI ≥25 = 19.9% (CG) and 11.1% (FBA); BMI ≥30 = 27.3% (CG) and 20.2% (FBA)]. Football athletes had significantly higher WT, BMI, FFM, and frequency of BMI ≥25 with lower %Fat and FM than CG (&agr; < 0.05). Linemen had the highest WT, BMI, FFM, %Fat, and frequency of BMI ≥25. Conclusions:The relationship between BMI and %Fat differed between CG and FBA. Using current BMI thresholds for obesity in FBA may result in misleading inferences about health risk.